Apear PGIP gene preferentially expressed during fruit development and regulated by salicylic acid
Haiyan Shi^*1,  Yuxing Zhang^*1 and Liang Chen² 

1、College of Horticulture, Agricultural University of Hebei, Baoding 071001, China
2、Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
This work was supported by The Education Department of Hebei Province Youth Fund (2010138) and the China Postdoctor Fund (2012M510761).
^*Corresponding author. E-mail: shyrainbow1980@yahoo.com.cn

Abstract
To elucidate the roles of genes during fruit ripening and softening, a fruit-predominant cDNA (designated PpPGIP1) encoding a polygalacturonase inhibitor protein (PGIP) was isolated from a pear (Pyrus pyrifolia Nakai. cv.Whangkeumbae) fruit cDNA library. The PpPGIP1 gene shares high sequence homology at the nucleotide level in the coding region and at the amino acid level with other plant PGIP genes. Subsequently, the corresponding PpPGIP1 gene was isolated from pear genomic DNA. Quantitative PCR analyses revealed that PpPGIP1 transcripts were preferentially accumulated during the developing fruit of pear. The PpPGIP1 expression was gradually up-regulated during fruit development, and its transcripts were accumulated at highest level in 150 d after full bloom fruit. In addition, PpPGIP1 gene was dramatically up-regulated in fruit by 0.02 mM salicylic acid for 12 h. These results suggested that the PpPGIP1 might be involved in regulation of fruit softening and in response to salicylic acid in pear.

Key words: pear (Pyrus pyrifolia); polygalacturonase inhibitor-like protein; fruit softening; gene expression; salicylic acid.